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Mazda i-ELOOP regenerative braking system using capacitors

This was interesting to see. Its similar to what a few mfgs are doing by fully powering up the alternator during braking, but they're using capacitors to be able to capture more energy. They're also bumping up the alternator output voltage to capture more energy as well (variable from 12-25V). They claim a max FE increase of 10% which is what we've seen be eliminating the alternator here on EM.

Mazda Improves Fuel-Saving Start-Stop System With Capacitors

Daox -

Quote:

Originally Posted by Daox (Post 287062)

Oooooooh, ultracaps in a big automaker drivetrain :

Quote:

Unlike batteries, which are very limited in how rapidly they can charge, or discharge, due to heat and chemistry constraints, capacitors can very rapidly store and discharge energy. The capacitor in Mazda’s system, the automaker says, can be fully charged in seconds. Other strengths of capacitors is that they’re easier to package, and they don’t deteriorate appreciably over time, as batteries do.

...

Capacitors have been examined for more than a decade as an energy-storage alternative to batteries, but the downfall of capacitors—or larger-scale ultracapacitors—is that they’re essentially one-trick ponies, with discharge rates that can’t be significantly extended. Many automakers are examining them as buffers to help increase efficiency in hybrids, and some have used them with fuel-cell vehicles—in earlier development versions of the Honda FCX fuel-cell vehicle, for example.

Mazda’s configuration makes sense for congested city-driving patterns, where rapid braking is typically followed by idling; and it’s in those following seconds that ancillaries can best use the extra power.

CarloSW2

Interesting, but will it work with a manual transmission (i.e. decel w/ clutch in)?

Quote:

Originally Posted by cfg83 (Post 287068)

Oooooooh, ultracaps in a big automaker drivetrain :

Well, they don't specifically say they're using ultracaps. All they say is this:

Quote:

The new system adds a 12-25-volt variable-voltage alternator, a low-resistance, electric double-layer capacitor, and a DC/AC converter.

If that is the definition of an ultracap I stand corrected. However, I would think they would make a bigger deal of it if that were the case.

Daox -

Quote:

Originally Posted by Daox (Post 287080)

Well, they don't specifically say they're using ultracaps. All they say is this:

Quote:

The new system adds a 12-25-volt variable-voltage alternator, a low-resistance, electric double-layer capacitor, and a DC/AC converter.

If that is the definition of an ultracap I stand corrected. However, I would think they would make a bigger deal of it if that were the case.

Yes, you are right, I am jumping to conclusions. I do think their "mazdacapacitor" design is fulfilling the same role in the drivetrain as an ultracap would.

CarloSW2

It would be interesting to see what kind of capacity that capacitor has in kWh, and what kind of current that alternator is pumping out at 25V.

I just saw a commercial about it and did a search here, and of course you guys have already discussed it.

My dream vehicle is an AWD station wagon with an electric drive train. I think the combination of ultracaps with batteries would allow for high energy takeup from braking, then using that same energy to help accelerate and recharge batteries.

Of course, in my dreams, the recharge connector would be in the back, so I could put a small diesel generator on a hitch platform or a small trailer for longer trips.

Mazda's use of capacitors (I assume Ultra) is one step closer to my dream.

Holy crap, this looks like it's pretty close to being commercially available. Good for Mazda!

25V alternator is a little disappointing though, with field coils at 12V you should be able to get over 30V in the 2000s (engine rpm). Still, improvement over 12V I suppose.

I wonder why they mention AC/DC converter. Could it be an inverter that feeds power back into the alternator (and uses it as a motor)?

...bet Mazda is taking the "cautious" approach and only using 25V because it's essentially a multiple of the common 12VDC lead-acid battery already available...super simplistic, but VERY co$t-effective, and CHEAP.

Quote:

Originally Posted by Old Tele man (Post 338968)

I don't think that's what's going on, because that article says the alternator is "variable voltage", aka there's probably a special charging mode at 25V, and otherwise it's pumping out regular 12V. I'm guessing it relies on the voltage converter to utilize the energy stored in the capacitor bank.